SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45f82da35ef0752cb605c6c7e3f06c35409152695b6090c0f06dcabdb3243211' 
  AND token = 'sM6XtNibWpgV9kwRuXxYueZk29rH6j/ZwE+Kqzl7Dw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}